This invention relates to a fermentation process for preparing (5R,6S,8S)-3-(2-aminoethylthio)-6-(1-hydroxyethyl)-7-oxo-1-azabicyclo[3.2. 0]hept-2-ene-2-carboxylic acid (I) which is useful as an antibiotic: ##STR1## The antibiotic of Structure I will be recognized as 8-epi-thienamycin (also known as desacetyl 890 A.sub.3). Thienamycin (II) is disclosed and claimed in U.S. Pat. No. 3,950,357 (Apr. 13, 1976): ##STR2## This patent disclosing and claiming thienamycin is incorporated herein by reference since 8-epi-thienamycin (I) is isolated from the very same fermentation broths that yield thienamycin and co-produced antibiotic, northienamycin, as described in commonly assigned U.S. Pat. No. 4,247,640,issued Jan. 27, 1981.
The compound of structure I is fully disclosed and claimed in commonly assigned U.S. Pat. No. 4,234,596 issued Nov. 18, 1980. To the extent that the cited commonly assigned U.S. Pat. No. 4,234,596 describes the antibiotic utility of I, it is incorporated herein by reference.